Indholdsfortegnelse for May/June 2020 i Horticulture

Spring: it’s the time for fresh starts, spruce ups and exciting changes for a garden. This spring, we can say the same is true for Horticulture and our website, HTTP://WWW. HORTMAG.COM. Let’s start with the print edition of Horticulture. It’s possible you’ve already noticed our first change. We’ve been able to switch to a heavier paper! We hope this makes your copy easier and more enjoyable to read and that it better shows the beautiful gardens and plants that our content contributors share. That brings me to our second change. It’s really more of a tweak. We sent a survey by e-mail to ask what kind of content Horticulture readers like and desire the most. The results clearly showed that articles about plants and written by professionals from garden-related fields…

BOB OSBORNE started Corn Hill Nursery in the 1980s, with an interest in grafting. He began with apples, but later shifted to roses. (The New Brunswick mail-order and walk-in nursery also offers a full range of trees and shrubs, fruiting plants, perennials and vines.) Remembering his start as a nurseryman, he says he was “too stubborn to quit, though it’s no way to get rich.” The first rose to pique his interest was a rugosa hybrid, and he soon found himself drawn to old roses. “They were much hardier than I thought, and easier,” he recalls. “I got hooked!” He started collecting cultivars, of which he now has more than 200. Corn Hill Nursery sits in USDA Zone 4b, with winter lows of –25 degrees (F). Bob remembers winters being…

Wind can be a problem in gardens because it can dry out the soil, break delicate plants and, if consistent, stunt growth or produce a deformed, leaning, lopsided shape. A garden open to frequent breezes presents a unique advantage, however. It’s the chance to add motion to the garden by incorporating flexible plants that can cope with wind in a very graceful way. Movement is an important garden element because it calls attention. The fluttering or swaying of leaves and stems catches the eye and causes one to focus in on that area of the garden. Certain plants add sound as they move, too. Flexible plants provide flexibility in placement. These tall but wispy plants can be placed toward the front of the bed or border without the fear that…

I LOVE THE FIERY KICK of hot peppers like cayennes, jalapeños and habaneros, but they can be a challenge to grow in my northern garden, where summers can be short. Over the years, I’ve found a few tricks to help these heat-loving plants establish quickly in spring and get a headstart on the growing season. First, pre-warm the soil. Warm-season crops like hot peppers, eggplants and melons grow best in soil with temperatures above 65 degrees (F). In my USDA Zone 5 garden, the soil can take weeks to warm up after the last frost, so for a few weeks before transplanting I cover it to hasten the process. I use clear or black plastic, stretching it taut over the soil surface and pinning or weighing it down. I leave…

Nurseryman Bob Osborne has trialed hundreds of roses for hardiness, disease resistance and overall performance and appeal. Here are a few that have made a deep impression: 1 ‘Oscar Peterson’ Bob notes this as a most disease-resistant cultivar, with interesting upright, shiny leaves and clusters of pink buds that open to semi-double white flowers. It remained in full bloom well into fall at the nursery. Introduced in 2016 as a member of the Canadian Artists series, it is hardy to USDA Zone 3b. 2 ‘Queen of Denmark’ A favorite for its excellent fragrance is ‘Queen of Denmark’, which has medium-pink flowers. This 1826 introduction is hardy to Zone 4a. 3 ‘Maiden’s Blush’ This very old cultivar blooms for a month, with excellent fragrance. Introduced around the year 1400, it has…

FLOWERING CURRANT RIBES SANGUINEUM An upright shrub hailing from the Pacific Northwest, flowering currant blooms in early spring with cascades of fragrant pink or red flowers. It is quick to grow and adaptable to sun or shade. The pretty flowers provide food for wintering hummingbirds in this shrub’s native area. HABIT: A deciduous shrub that reaches six to eight feet tall and about six feet wide. It can create a small thicket as it spreads by suckers, but it is not considered aggressive. ORIGIN: Open woods at low elevations in the Pacific Northwest, northern California, Idaho and British Columbia. HOW TO GROW IT: Full sun will prompt the heaviest flowering from this currant species, but it can take part sun or bright shade and will bloom there. It tolerates drought…

CALYCANTHUS FLORIDUS CULTIVARS ‘Athens’ No list would be complete without this Mike Dirr–named beauty. It’s a touch smaller than the straight species, and its real standout attribute is the yellow-chartreuse color of the blooms. Nice fragrance in bloom and good yellow fall foliage color. ‘Michael Lindsey’ Hands-down best form for a straight species selection. It has deep green, sharply pointed leaves that remain glossy all through the summer then turn a glowing golden color. And the flowers are as fragrant as any other. Named and introduced by my Louisville, Ky., gardening friend Allen Bush. ‘Burgundy Spice’ This Pleasant Run Nursery (N.J.) introduction has been an absolute standout in our trials at Yew Dell Botanical Gardens. Typical size, shape and flowers for the species but with deep and vivid burgundy coloration…

You can make certain plants less susceptible to wind damage by performing the same technique that’s used to avoid the need to stake them. “The Chelsea chop,” so named because it’s done just after the Chelsea Flower Show in its country of origin, England, is an appropriate strategy for tall sedums, border phlox, coneflowers, tickseed and goldenrod, to name a few. Simply cut a third to a half of each stem off in late spring. The plants will flower later, but they’ll also remain shorter and bushier, with more flower buds to boot. If the Chelsea chop seems a bit drastic, you might try it on just a few plants within a grouping this year, to see how they do, or try it just on those plants that stand in…

1. SIBERIAN SQUILL Scilla siberica, Othocallis siberica. Originally from southern Russia, this bulb naturalizes beautifully. Deep blue, nodding, bell-shape flowers with blue anthers bloom in early spring on a three- to six-inch scape. Strappy, medium green leaves follow. Full sun to part shade; USDA Zones 2–8. 2. ALLIUMS Allium spp. and cvs. From wild chives, garlic, leek, shallot, scallion and onion to all the wildly sculptural ornamental onion cultivars, there is likely an allium for every garden and every bee. Flowering umbels come in shades from white to pink and purple. Many are edible, as well as being rodent and deer tolerant. Full sun to part shade. Zones 3–8. 3. MOUNTAIN-MINT Pycnanthemum muticum. Native to the eastern United States, this herbaceous perennial hums with bees when it blooms in July…

VESSELS WITH VARIETY Pots and containers these days range from standard terracotta to glazed, metal, hypertufa, stone and ceramic, and they come in a myriad of colors, textures, finishes, shapes and sizes. Allowing your plant material to be as varied as the vessel is a fantastic way to break out of the mundane and enhance your garden’s mood and style. Think houseplants, dwarf shrubs, small conifers and ornamental trees used in combination or as single specimens. Mixed plantings comprising perennials and annuals lend an element of flexibility and intrigue. Grasses, agaves, other succulents and vines all add structural creativity and flair. It may prove wise to limit the number of plants in a single container, considering size and spacing of the plants at maturity. A vessel with a couple plants…

Plant. May is prime time for planting vegetable seeds and seedlings in most of North America. As you plant your family favorites, don’t be afraid to try a few new varieties or crops. I love experimenting in my vegetable plot, and I’m always on the lookout for varieties with outstanding characteristics like improved flavor, disease resistance or early maturity. Mulch. I’m a big believer in mulching around my vegetable plants, which not only prevents weeds but also holds soil moisture and can reduce the spread of soil-borne diseases like early blight on tomatoes. I use straw or shredded leaves, placing a three-inch layer around crops like tomatoes, squash, cucumbers, ground cherries and broccoli. Sow. As I move seedlings from grow-lights to garden, I like to fill the empty space beneath…

LET’S SAY THAT the fundamental currency for exchange in the universe is energy. Even paper and digital money we handle each day is a proxy exchanged for and representing the energy we spent on someone else’s behalf. The plant kingdom (with extremely rare exception) is very special in that its members directly use the energy from sunlight in order to grow. This process is called photosynthesis. People piggyback on plants to gather the energy we need. We call it harvesting. The energy from the sun is stored in the grains and vegetables we consume. In order to produce those grains and vegetables, plants must invest a significant amount of their energy into the development of their root systems. Why? Well as it turns out, soils are in fact not quite…

When you think “wildflower,” what vision comes to mind? For the vast majority of American gardeners, it’s certainly not a 12-inch, hot pink, pinwheel-like hibiscus blossom. Yet there are hibiscus species native to much of temperate North America, and they have given rise to varieties that thrive as perennials in gardens as cold as USDA Zone 4. Hybrid hibiscus entered the garden scene in the 1950s with Robert Darby’s ‘Lord Baltimore’, derived from several native species, including Hibiscus coccineus and H. moscheutos. The ’60s and ’70s saw additional hybrids enter the market, and later a slew of exciting introductions appeared from the famed Fleming brothers of Nebraska, including the still-treasured bronze-leaved ‘Kopper King’. Recent years have seen a wave of novel cultivars, particularly from Michigan-based breeder Walters Gardens, that are…

there are five types of nearly flat plants in my garden. Each one suppresses weeds like a champ, remains durable under foot and returns year after year with no tending or fuss. Three of them were planted by no one, biding their time in the soil’s seed bank for an opportunity to flourish. The other two were planted by humans. I may or may not have been the one to plant those. PATIENT AND PRIMITIVE An area of open ground in the shade of my house once held a group of raised beds. To keep the weeds down, each year I installed untold yards of mulch between the boxes. Then one summer I skipped the mulch, perhaps to give my wallet and my back a break. Of course, by doing…

Another way to beat the wind is to simply block it with sturdy fencing or a hedge. To determine how much space a structure, tree or shrub protects, multiply its height by two and then picture that measurement stretching out from the base of the windbreak. Anything planted within that limit will be protected from the wind. Junipers, pines and spruces can be effective and durable choices for an evergreen windbreak, while shrubby dogwoods, native cherries, crabapples, serviceberry (Amelanchier alnifolia) and elderberries (Sambucus) are some options for a deciduous windbreak of small trees and large shrubs. Shrubs and mounding perennials offer another solution to wind that can be a very effective design element. Just as you might train a climbing rose or clematis to grow through a shrub rather than…

WELCOME POLLINATORS Our CFO/COO here at the Gardens is a Master Beekeeper and her enthusiasm is contagious. It is exciting to see how popular pollinator gardens are becoming, especially as we become more knowledgeable about the lives of bees and the challenges they face. Luckily, these pollinators are easily provided for with a little planning. Bees especially need support early in the season. Why not plant a lawn with Siberian squill? A blue pollen-covered bee, after all, is a sight to behold! Other early-blooming plants and trees like witch hazels or lindens also offer variety early on. An herb or kitchen garden can be as delightful to bees as it is to humans. St. John’s wort and anise are especially attractive to bees and not as common as mint or…

1. PAPER BUSH Edgeworthia chrysantha. This attractive shrub offers fragrant flowers borne on bare stems in late winter to early spring. Its tropical-looking leaves, which resemble those of plumeria, look great in summer. Full sun to part shade; USDA Zones 7–10. 2. JAPANESE CAMELLIA Camellia japonica. We grow this outdoors year-round here in the Southeast, choosing from a multitude of cultivated varieties. From December to March, the glossy, dark green leaves are a backdrop to the flowers, which can be found in all shades of white, pink and red. Part shade; Zones 7–9. 3. BLACK MONDO GRASS Ophiopogon planiscapus ‘Nigrescens’. This is a nice diversion from Liriope, with a similar usage in the garden. It provides beautiful contrast when planted alongside silver, yellow, gold, orange or red foliage and flowers.…

THE LONGER WE GARDEN, the more we know. Only makes sense, right? Sadly, this “more” we know is offset by a couple of cruel factors. First is an up-close and personal awareness of the ravages of time. Yep, the longer we garden, the older we get; and, of course, the older we get, the more we forget. But there’s also this: The more we know about gardening, the more we know how little we know of all there is to know. Kind of ironic, no? Sadly, reaching this wizened state is inevitably a slow and eventually humbling process. The unfortunate part of that last sentence is the unassuming word “eventually.” It asserts that through our progression toward enlightenment—which, you’ll remember, means we got just enlightened enough to know we really…